Grinding and polishing method and apparatus



GRINDING AND 'POLISHING METHOD AND APPARATUS FIG.1

INVENTOR. George E. Bonin ATTORNEY Dec. 13, 1966 G. E. BoNlN 3,290,828

, GRINDING AND POLIHING METHOD AND APPARATUS Filed June 1, 1964 u 5 Sheets-Sheet 2 PIG. 5

FIG. 6

FIG. 3

INVENTOR.

George E. Bonin ATTORNEY De. 13, 1966 I G. E..` BONIN GRINDING AND POLISHING METHOD AND APPARATUS Filed June 1, 1964 5 Sheets-Sheet 3 FIG. Lr

INVENTOR. George E. Bonin ATTORNEY United States Patent O 3,290,828 GRINDING AND PLISHHNG METHOD AND APPARATUS George E. Bouin, Addison, N.Y., assignor to Corning Glass Works, Corning, N.Y., a corporation of New York Filed June 1, 1964, Ser. No. 371,297 11 Claims. (Cl. 51-73) This invention relates to animproved method of an apparatus for finishing contoured surfaces, and more particularly t-o novel .process and apparat-us for uniformly pumicing and polishing frangible curvilinear glass surfaces with high removal rates and low loading pressures.

In the past, it has been customary to pumice and polish curvilinear` glass surfaces, such as TV panels and caps, by utilizing a pneumatically inflated flexible cylindrical sleeve. The pneumatic sleeve is rotated about its longitudinal axis and is posit-ioned to contact a panel or cap rota-ted about a vertical axis. When pumicing, the outer surface of the sleeve is provided with rubber or the like, whereas when polishing, the sleeve is` 4provided with a felt outer surface.

Although the pneumatic sleeve deformed to approximate the contour of the convex rotating workpiece, and therefore provided some degree of polishing or pumicing, it has not been completely satisfactory for various reasons. One disadvantage resides in the fact that complete and continuous contact between the sleeve and the surface of the article cannoty be maintained, resulting in intermittent or partial contact therebetween thus producing a `rather low stock removal rate, in the order of about grams per minute. In comparison, the present invention may remove up to approximately 75 grams per minute. A further disadvantage with the pneumatic sleeve type of removal is the fact that it necessitates excesively high power requirements f-or the amount of material removed. Further, the point loading obtained by the slaping pneumatic ysleeve in effect produces zone removal, which not only induces breakage, but also results in surface aberrations which, of course, detrimentally affect the usefulness of optical or TV panels.

Other methods utilized in the past to grind and polish curvilinear surfaces, such as convex TV panels and caps, included the uti-lization of a hand pumice wheel. Not only is this method extremely time consuming and expensive, but also due to human error the results are not necessarily accurate.`

The present invention obviates the above-noted disadvantages with the know finishing devices by enga-ging the curvilinear surface of a rotating workpiece to be finished with a moving closed-circuited or continuous interior surface of substantial length. The interior surface is flexible and preferably contoured to the curvature of the workpiece to uniformly encompass the surface thereof as it continuously passes thereover. A slurry is recirculated and continuously provided between the workpiece and continuously moving surface not only for stock removel but also for preventing overheating of the surface or workpiece.

It thus has been an object of my invention to provide an improved method of and means for finishing a contoured surface of fnangible material such as glass, by effecting a complete contact of the ent-ire surface with a finishing device, thus requiring a minimum tot-al pressure on the surface and resulting in even loading under relatively small area presures.

An additional object of the invention has been to provide an improved finishing operation for curvilinear ware surfaces wherein improved removal rates are obtained without applying excessive local pressures upon any portion of the ware.

3,293,828 Patented Dec. 13, 1966 A further object of the invention has been to provide an improved finishing operation having a large work area to ware surface ratio, thus providing for adequate c-ooling of both the work area and ware surface.

These and other objects of my invention will become more zapparent to those skilled in the art from the following disclosure and accompanying drawings in which,

FIGURE 1 is a side elevational view partially in section of an laparatus embodying my invention.

FIGURE 2 is a front elevational view partially in section of the device shown in FIGURE 1.

FIGURE 3 is a top plan View of the apparatus shown in FIGURE 1.

FIGURE 4 is a schematic diagram illustrating one method of controlling the apparatus shown in FIGURES 1 through 3.

FIGURE 5 illustrates a further embodiment of the invention.

FIGURE 6 is a schematic illustration of an additional physical embodiment of the invention.

Referring now t-o the drawings, and particularly FIG- URES l, 2 land 3, finishing apparatus embodying my invention is shown at 10. The machine 10 has a supporting base comprising a pair of I beams 11, 12 provided with a plurality of U-shaped cross beams 13, 14 and 15. Cross beams 14 and 15 have a pair of A frames 16 and 17, respectively, which support a bearing mount platform 1S. A pair of bearing housings 19 mounted on platform 18 rotatably support -a spindle '20.

As shown in FIGURE l, one end of the spindle 20 has a flange or disc-shaped plate 21 rigidly secured thereto. The disc 21 i-s secured to a back plate 22 of a rotatable drum of cylinder assembly 23. The assembly is provided with an annular rim portion 24 having a contoured inner surface. The rim .portion is `shown provided with a slit Iopening 2S formed in its largest diameter to facilitate centrifugal drainage of slurry from the drum as hereinafter described, although other drainage openings may be provided for this purpose. The annular rim portion 24 may be formed from a plurality of segments, as shown, or it may be in the form of a solid contoured rim having suitable drainage openings therein. A plurality of flexible liners 26 overlie the inner contoured surface of the drum assembly to provide la continuou-s or closed-circuited contoured work area on the internal surface of the drum for continuous movement across the entire surface of a contoured workpiece.

The rotating drum assembly 23 is surrounded by a station-ary outer shell or splash guard 27 to collect pumicing or polishing slurry expelled from the rotating drum. The outer shell is provided with la discharge drain or outlet 28 to return the slurry collected in the shell 27 to a slurry tank 29. If desired, a screen or other suitable means may be provided lto remove contamination and other foreign matter from the slurry delivered to the tank 29. A mixer 30 is provided to a-gitate the slurry in tank 29 for the purpose of maintaining a homogeneous slurry. A pump P returns the slurry to the interior of the rotatable drum or cylinder assembly 23 by means of conduits 31.

The liners 26 are made of any suitable material so as to conform to the contour of the article to b'e pumiced or polished. The liner may be made of such materials as neoprene, neoprene and cork, neoprene and sizal, woven fabrics and rubber, felt on rubber, coa-ted abrasives including diamond-coated mesh, or Walrus hide. The contour of the internal surface of the annular rim portion 24 is preferably provided with substantially the same .radi-us as the radius of the rotatable drum assembly 23 taken from its axis of rotation. With the workpiece rotated about Ian axis substantially perpendicular to a tangent which contacts the contoured surface of the workpiece substantially centrally thereof, a su-bstantially spherical surface results which in the case of TV caps and panels is yclose to the contour of the article being worked. If the various radii are not substantially identical, zoning and inefficient stock Iremoval will result. However, since the liner pads 26 are extremely flexible, minor diiferences in lthe two radii will be compensated for by the exibility in the pads, thus producing operable results. f

A pulley32, secured to the end of spindle opposit rotating drum 23, is driven through various transmitting means by an electric motor 33 to impart rotation to the rotatable drum 23. As shown, a belt 34 transmits power from the output shaft of electric motor 33 to the input shaft of a suitable speed converter 35, the output shaft of which is supplied with a pulley or sheave 36 having a belt 37 transmitting rotation to the pulley 32. It thus can be seen, that the rate of rotation of drum 23 may be controlled by varying the speed of motor 33.

A work spindle carriage assembly 40 is suitably mounted upon an overarm support frame 41 comprising a pair of uprights 42 and a cross bar 43. A pair of mounting blocks 44 positioned on cross bar 43 are each provided with a pillow block 45 for mounting a stationary guide shaft 46. A cylinder 47 having a piston rod 50 operated by control ports 48, 49 connected to a suitable uid power source, is also secured to cross bar 43 by means of a stationary :support bracket 51 and ball joint 52. The forward end of piston rod 50 is connected by a ball joint 53 to a platform 54, slidable along the stationary guide shaft 46 by means of guide blocks 54 and the cylinder 47.

A suitable motor 55 having gear reduction means is mounted on the platform `54 and has a sheave 56 on its output shaft. The sheave -56 is provided with a pair of belts 57 which extend within a guide arm 58 and about fa second pulley or sheave 59 keyed onto a shaft 60 carried for rotation by a support 61. The shaft 60 operates through a standard right-angle drive unit 62 to rotate a vertical shaft 63 upon which a work holder or support table 64 is keyed. As shown particularly in FIGURES l and 3, a workpiece such as a TV panel or cap 65 may be positioned upon the work holder or support table 64. The Work holder may be provided with a plurality of grooves to facilitate the proper positionment thereon of various sized workpieces.

From the foregoing, it can be seen that rotational movement delivered to sheave 56 by motor 55 is transmitted to sheave or pulley 59 by means of the double belts 57. Sheave 59, in turn, being keyed to -shaft 60 rotates shaft 60, and through a standard right-angle drive unit 62 rotates vertical shaft 63, upon which the work holder or support table 64 is keyed. It should be noted that the vertical axis of the shaft 63, about which the workpiece is rotated, intersects the workpiece 65, positioned on the holder 64, substantially centrally thereof and substantially at a right angle to a tangent which contacts a central portion of the contoured surface of such workpiece.

The work spindle carriage assembly 40 is not only slidable Ialong the stationary guide shaft 46 to position the work holder or support table in and out of the rotatable drum 23, but is also pivotable about the shaft 46 to facilitate the positionment and release of the contoured workpiece 65 with respect to the continuous work surface presented by the contoured flexible liners 26. A column or shaft `66, secured to I beam 12 by a universal joint 67, has a mounting b-ase 68 for securing a cylinder 69 thereto. The cylinder 69, which is provided with suitable control ports 70 and 71, has la piston rod 72 connected to guide ar-m 58 by means of a pivotal joint 73. Thus, by actuating cylinder 69, piston 72 pivots arm v58 and accordingly the work spindle carriage assembly 40 about shaft 46 for inserting a ware item 65 upwardly into operating position within tle drum 23, and for lowering it from the continuous interior work surface for facilitating the removal of the workpiece from the drum. The universal joint 67 allows movement about both lateral and transverse directions, thus not only facilitating the pivotal movement of the assembly about shaft 46, but also the previously described longitudinal movement.

In order to control the various movements of the work spindle carriage assambly 40 and energize the motor 55 at the proper time, various limit switches are positioned on the apparatus which are energizable by various carriage positions. For example, when the carri-age assembly 40 is moved within the drum 23, the platform 54 contacts a limit switch 7- 5 (shown in FIGURE 3) which actuates a valve energizing cylinder 69 for pivoting the assembly 40 upwardly into operable position in the drum 23. As the assembly reaches its end positi-on by pivoting about the shaft 46, a second limit switch 76 (FIG. 2) is actuated to not only start motor 55 but also energize a timer or delay switch T (see also FIG. 4) for actuating cylinder 69 after a period of time to pivot the Iassembly 40 downwardly. As the arm 58 pivots downwardly about shaft 46, a further limit switch 77 (FIG. 2) energizes a solenoid valve to activate cylinder 47 for moving the assembly 40 along shaft 46 outwardly of the drum 23. If desired, an additional limit or safety switch 78 may be utilized and secured to cross bar `43, so as to be actuated when the carriage 40 is moved to its outermost position shown in dash lines in FIGURE l, to open the circuit and deenergize the system.

Referring now to the complete operation of the apparatus shown in FIGURES l through 3, reference is made to the pictorial or schematic illustration shown in FIGURE 4. Initially a switch 79 is closed to energize motor 33, and a switch 80 is closed to energize both the pump P and the mixer 30, all of which run continuously during the operation of the device. Initially, the apparatus 10 will be in its loading position, with the work spindle carriage assembly in its -outermost position as shown by the dash lines of FIGURE 1, and also in its lowermost position such as indicated by the dash lines in FIGURE 2. A ware piece, such as a television panel or cap is positioned upon the work holder or support table 64.

A starter button 81 is then pushed to energize a fourway solenoid valve 82 for supplying fluid to inlet 49 of cylinder 47 so as to retract piston rod 50 and move the work spindle carriage assembly along drive shaft 46 to position the work holder within the drum 23. When the safety limit switch 78 is utilized in the circuit as shown, it is necessary to simultaneously push normally-open reset button 83 to complete the circuit through solenoid valve 82. When the piston rod 50 has reached its desired innermost position, the limit switch 75 is engaged such as by platform 54 and actuated to energize a second four-way solenoid valve S4 which supplies uid to inlet 71 of cylinder 69 to move piston rod 72 to its outermost desired position as shown in dash lines in FIGURE 4. When the piston rod 50 is retracted, safety limit switch 78 moves to its normally closed position thus completing the circuit through limit 75 and solenoid valve 84.

When the piston rod 72 is in its outermost desired position the ware piece, positioned upon the support table 64, is maintained in operable contact with the inner liner lof the drum 23 under a yconstant predetermined pressure as shown in full lines in both FIGURES l and 2, and limit switch 76 is contacted by the pivotal movement of the carriage 40. The closing of limit switch 76 not only energizes motor 55 to rotate the work holder 64, but also a delay timer T. After a predetermined period of operating time, the timer T energizes the solenoid valve 84 to supply fluid to inlet 70 of cylinder 69 and thereby retract piston rod 72 thus returning limit switch 76 to its normally open position and deenergizing motor 55 and timer T. As the rod 72 reaches its full retracted position, the ware piece on work holder 64 is removed from engagement with the inner liner of drum 23 with the work spindle carriage assembly pivoted downwardly as shown by the dash line position of arm 58 in FIG- URE 2.

As the arm 58 moves downwardly, limit switch 77, positioned thereon, is closed to energize four-way solenoid valve 82 through norm-ally closed safety limit switch 78, to supply fluid to inlet 48 of cylinder 47 and move piston rod 50 to its outermost position. As rod 50 moves outwardly it slides the work spindle carriage assembly along guide 46 and removes the work holder from the drum 23. Upon reaching its outermost position safety limit switch 78 is contacted by the carriage 'assembly 40 to open such switch deenergize the system. The finished work piece is then removed from the holder 64 and a new workpiece to be finished placed thereon and the cycle again repeated.

As previously mentioned, the drum 23 is continuously rotated during the entire operation, and pump P continuously supplies a pumicing or polishing slurry to the internal fiexible liners 26. The internal surface of the drum forms a contoured-continuous or closed circuited internal surface which continuously passes over the rotating workpiece when it is in its operable position. Due to the large work area to ware surface ratio, and the presence of abundant cooling in the form of a light slurry, overheating of the wheel surface or ware surface is prevented. In addition, the long work surface provides a good distriubution of the slurry while the contour of such inner work surface facilitates complete coverage of the ware thus requiring less total pressure on the ware and preventing excessive local pressure. The placement of the various liners 26 about the inner surface of the drum 23 facilitate the centrifugal drainage of the slurry past end portions of the liners and outwardly through the drainage slit 25 formed in the annular rim portion 24. T-he slurry is collected by the outer shell or splash guard 27 and returned to the slurry tank 29 by means of discharge drain or outlet 2S. The mixer 30 provides a homogeneous mixture of the slurry for recirculation by pump P back from the drum 23.

To illustrate the effectiveness of my invention, a 23 television cap was positioned in'the machine as shown in FIGURE 1. A slurry flow of 2 gallons per minute having a ratio of 3 parts water to 1 part pumice was applied to the drum. With a force on the panel of 71S pounds, 65 grams per minute were removed from the face of the panel. This compares with only 30 grams per rninute obtainable with the standard lap machine which requires a force of between 2000 and 3000 pounds on the face of the panel. It thus can be seen that higher removal rates with less force on the panel is obtainable with my invention. Accordingly, thinner articles may be nished without breaking due to the relatively small force applied to the panel with my improved apparatus.

FIGURE 5 schematically illustrates a further embodiment of the invention wherein a rotatable work holder assembly 140 is positioned within a rotating drum 123 which may be rotated about either a horizontal or vertical axis. The work holder assembly 140 is provided with a plurality of rotatable work holders or support tables 164. The support tables 164 may be indexed about a central axis during the finishing operation for consecutive presentation to a loading and unloading station. At such station, the support table would be retracted radially, such as by a piston-bellows arrangement 165, and moved outwardly of the drum such as by a suitably driven dovetail arrangement 166 to position a workpiece on and remove a finished one from each table 164. If desired, it is within the scope of this invention to rotate the drum 23 or 123 about a vertical axis rather than a horizontal axis.

FIGURE 6 shows a further embodiment of `the invention wherein a frusto-hemispherical member 223 rotates about a vertical axis to provide a contoured internal 6 closed-circuited or continuous work path for a plurality of work holders 264, which are rotated about an axis perpendicular to a tangent centrally contacting the contour of the workpiece positioned on the work holder 264. A platform 265 indexes about a vertical axis to position the various work holders 264 at loading and unloading stations wherein they are slid radially inwardly such as along tracks 246 to release the workpiece from the work surface and facilitate the removal of a finished workpiece and replacement of an additional workpiece to be finished.

Although I have disclosed the now preferred embodiments of my invention it will be apparent to those skilled in the art that various changes and modifications may be made thereto without departing from the spirit and scope thereof, as defined in the appended claims.

I claim.

1. An improved method of finishing contoured surfaces of a frangible article which comprises, rotating such a frangible article about an axis perpendicular to a tangent centrally contacting a curvilinear surface of such article to be finished, 'and simultaneously continuously passing an endless contoured internal work surface having a concave transverse cross section over the surface of the ware article to be finished.

2. An improved method of pumicing and polishing curvilinear surfaces of glass articles comprising, rotating such a glass article about an axis substantially perpendicular to a tangent contacting a central portion of the curvilinear surface to be finished, and simultaneously continuously passing a circular internal work surface having a radius substantially equal to the radius of the curvilinear surface to be finished over such curvilinear surface by rotating such work surface about an axis centrally of such circular work surface.

3. An improved method as defined in claim 2 wherein the axis of said circular work surface is perpendicular to the axis of rotation of said work piece.

4. Improved apparatus for finishing contoured surfaces of frangible articles which comprises, means for rotating a frangible article about an axis perpendicular to a tangent contacting a central portion of the contoured surface to be finished, rotating rneans providing an internal continuous work surface, said work surface having a concave transverse cross-sectional configuration substantially cornplementary to the surface to be nished, and means positioning the rotating workpiece in engagement with said rotating continuous internal work surface.

5. Apparatus for finishing curvilinear surfaces of glass articles which com-prises, support means for holding an article to be finished, means for rotating said support means about an axis perpendicular to a tangent contacting a central portion of the curvilinear surface to be finished, a hollow rotatable body, said body having an interior surface portion contoured to complement the curvilinear surface to .be finished, said interior surface portion forming a continuous annular internal work surface having a radi-us substantially equal t0 the radius of the curvilinear surface to be finished, means for rotating said body about an axis centrally of said annular work surface, and means for positioning an article Vto be finished while being rotated about said first-mentioned axis on said work holder in contact with said rotating work surface to unifonmly contact the entire curvilinear surface of the article to be finished.

6. Improved apparatus as defined in claim 5 wherein said body is a rotatable circular drum rotated about the axis of such circle.

7. An improved method of nishing contoured surfaces of frangible articles which comprises, providing a continuous internal work surface having a curvilinear transverse cross-sectional contour substantially complementary to the curvature of the surface to be finished, continuously passing such endless work surface through a path contoured to complement such surface to be d finished, rotating an article to be finished about a central axis perpendicular to a tangent contacting its contoured surface to be finished, and engaging the contoured surface of such rotating a-rticle While maintained in a fixed orientation with the continuous internal Work surface while simultaneously continuously passing such work surface through such contoured path.

8. An improved method of finishing curvilinear surfaces of glass articles which comprises, providing a continuous internal Work surface having a contour substantially equal to that of the curvilinear surface to be finished, continuously rotating such endless internal Work surface about a central axis such that a radius extending from such axis to the Work surface is substantially identical to the radius of the curvilinear sur-face to be finished, rotating an article about an axis substantially perpendicular to a tangent contacting a central portion of its curvilinear surface to :be finished, and relatively applying the rotating curvilinear surface to be finished to the rotating internal continuous surface under a predetermined pressure for a desired period of time.

9. Apparatus for finishing curvilinear surfaces of glass articles which comprises, a rotatable body member, said |body member having an endless internal Work surface, rneans for rotating said internal work surface about a central axis, Work holder means for supporting an article to be finished, means for lcontinuously rotating said Work '8 holder means about an axis extending centrally of t-he surface to be finished and perpendicular -to said central axis, means for moving said Work holder means parallel to said first-mentioned axis to position said Work holder means Within and remove it from said body member, and lrneans for imoving said Work holder uneans Itransversely of said first-mentioned axis to operatively engage an article to be finished With said endless internal Work surface and remove it therefrom.

10. Apparatus as defined in claim 9 wherein means are provided for supplying a slurry to said endless inte-rnal Work surface, for draining slurry from such surface, and for recirculating such slu-rry back to such surface.

11. Apparatus as defined in claim 9 wherein said body is a circular drum having a radius substantially equal to the radius of the curvilinear surface to be finished and a contoured internal surface also provided with a radius substantially equal to the curvilinear surface to be finished.

References Cited by the Examiner UNITED STATES PATENTS 1,202,013 10/1916 Ainsley 51-73 ROBERT C. RIORDON, Primary Examiner. y

L. S. SELMAN, Assistant Examiner. 

5. APPARATUS FOR FINISHING CURVILINEAR SURFACES OF GLASS ARTICLES WHICH COMPRISES, SUPPORT MEANS FOR HOLDING AN ARTICLE TO BE FINISHED, MEANS FOR ROTATING SAID SUPPORT MEANS ABOUT AN AXIS PERPENDICULAR TO A TANGENT CONTACTING A CENTRAL PORTION OF THE CURVILINEAR SURFACE TO BE FINISHED, A HOLLOW ROTATABLE BODY, SAID BODY HAVING AN INTERIOR SURFACE PORTION CONTOURED TO COMPLEMENT THE CURVILINEAR SURFACE TO BE FINISHED, SAID INTERIOR SURFACE PORTION FORMING A CONTINUOUS ANNULAR INTERNAL WORK SURFACE HAVING A RADIUS SUBSTANTIALLY EQUAL TO THE RADIUS OF THE CURVILINEAR SURFACE TO BE FINISHED, MEANS FOR ROTATING SAID BODY ABOUT AN AXIS CENTRALLY OF SAID ANNULAR WORK SURFACE, AND MEANS FOR POSITIONING AN ARTICLE TO BE FINISHED WHILE BEING ROTATED ABOUT SAID FIRST-MENTIONED AXIS ON SAID WORK HOLDER IN CONTACT WITH SAID ROTATING WORK SURFACE TO UNIFORMLY CONTACT THE ENTIRE CURVILINEAR SURFACE OF THE ARTCLE TO BE FINISHED. 